title: Hyperinsulinemia stimulates angiogenesis of human fetoplacental endothelial cells: a possible role of insulin in placental hypervascularization in diabetes mellitus.
abstract: BACKGROUND
  The insulin/IGF system regulates fetal and placental growth and development. In a pregnancy complicated by maternal diabetes, placentas are hypervascularized and fetal insulin levels are elevated. In the fetal circulation, insulin can act on the placenta through insulin receptors present on the fetoplacental endothelial cells.
  
  
  OBJECTIVE
  We hypothesized that insulin exerts proangiogenic effects on the fetoplacental endothelial cells, thereby contributing to the placental hypervascularization in diabetes.
  
  
  METHODS
  The effect of insulin on angiogenesis and proliferation of human fetoplacental endothelial cells was investigated by a 2-dimensional network formation assay, staining for actin fibers, automatic cell counting, and cell cycle analysis. The signaling pathways involved were identified using antibodies against activated signaling proteins and pharmacological inhibitors.
  
  
  RESULTS
  Insulin enhanced network formation by 23% (P < .05%) and caused actin reorganization. Insulin stimulated (P < .05) phosphorylation of insulin receptor (+320%), and insulin receptor substrate-1 (+140%), Akt (+177%), glycogen-synthase kinase-β3 (+70%), and endothelial nitric oxide synthase (eNOS; +100%) increased nitric oxide production and activated Ras-related C3 botulinum toxin substrate 1 (Rac1). Insulin did not induce ERK1/2 phosphorylation or proliferation. Inhibition of phosphatidylinositol 3-kinase, eNOS, and Rac1 signaling abolished the effects on network formation.
  
  
  CONCLUSIONS
  Elevated fetal insulin levels may contribute to the placental hypervascularization in diabetes via the phosphatidylinositol 3-kinase/Akt/eNOS pathway and involve Rac1. However, insulin does not stimulate proliferation and may need to cooperate with other growth factors.
authors.affiliation: Department of Obstetrics and Gynecology, Medical University of Graz, Auenbruggerplatz 14, 8036 Graz, Austria.
authors.forename: Luciana
authors.initials: L
authors.lastname: Lassance
authors.forename: Heidi
authors.initials: H
authors.lastname: Miedl
authors.forename: Markus
authors.initials: M
authors.lastname: Absenger
authors.forename: Francisca
authors.initials: F
authors.lastname: Diaz-Perez
authors.forename: Uwe
authors.initials: U
authors.lastname: Lang
authors.forename: Gernot
authors.initials: G
authors.lastname: Desoye
authors.forename: Ursula
authors.initials: U
authors.lastname: Hiden
mesh_terms: D000199:Actins / Q000187:drug effects / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D006946:Hyperinsulinism / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010766:Phosphorylation; D010920:Placenta / Q000098:blood supply / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011247:Pregnancy; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011972:Receptor, Insulin / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D000199:Actins; C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D052250:Nitric Oxide Synthase Type III; D011972:Receptor, Insulin; D000071679:Glycogen Synthase Kinase 3 beta; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; D020830:rac1 GTP-Binding Protein